A communication system can be seen as a facility that enables communication sessions between two or more nodes such as fixed or mobile devices, machine-type terminals, access nodes such as base stations, servers and so on. A communication system and compatible communicating entities typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. For example, the standards, specifications and related protocols can define the manner how devices shall communicate, how various aspects of communications shall be implemented and how devices for use in the system shall be configured.
Users can access the communication system by means of appropriate communication devices. A communication device of a user is often referred to as user equipment (UE) or terminal. A communication device is provided with an appropriate signal receiving and transmitting arrangement for enabling communications with other parties. Typically a device such as user equipment is used for enabling receiving and transmission of communications such as speech and content data.
Communications can be carried on wireless carriers. Examples of wireless systems include public land mobile networks (PLMN) such as cellular networks, satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). In wireless systems a communication device provides a transceiver station that can communicate with another communication device such as e.g. a base station of an access network and/or other user equipment. The two directions of communications between a base station and communication devices of users have been conventionally referred to as downlink and uplink. Downlink (DL) can be understood as the direction from the base station and uplink (UL) the direction to the base station.
Various control information may need to be signalled between the parties. Control information is typically communicated on control channels, for example on physical uplink control channel (PUCCH) or physical downlink control channel (PDCCH). Furthermore, a large portion of the control signalling may be conveyed via PDSCH/PUSCH (physical downlink shared channel/physical uplink shared channel) as part of higher layer signalling.